Adhesive composition and use thereof

ABSTRACT

The invention provides adhesives comprising at least one polymer component which contains at least 65 weight percent propylene, at least one nucleator and at least one functionalized wax. The inventive adhesives have increased heat resistance and decreased set-time, making them particularly well suited for assembly and packaging applications.

FIELD OF THE INVENTION

The present invention relates to adhesives that comprise a polymercomponent, at least one nucleator, and at least one functionalized wax.More particularly the invention relates to adhesives that have increasedheat resistance and decreased set-time, making these adhesivesparticularly well suited for assembly and packaging applications.

BACKGROUND OF THE INVENTION

Adhesives are applied to substrates and are widely used for variouscommercial and industrial applications, such as product assembly andpackaging.

Hot melt adhesives are widely used in the packaging industry to sealcardboard cases, trays and cartons. Some packaging applications requirean adhesive to maintain a strong bond to a substrate under extremes ofstress and shock in handling, and high temperatures and humidity.Moreover, cases and cartons often encounter very high temperaturesduring transportation, so adhesives having sufficiently good heatresistance are required in these applications. “Sufficiently good heatresistance” is to be understood to mean that the bonded adhesivemaintains fiber tear at elevated temperature, e.g., greater than 52° C.(125° F.), and hence should not immediately soften when acted upon byelevated temperature, with the result that the adhesive bond loosensand/or the bonded parts shift with respect to one another.

Recent developments in polymer technology have allowed for a newgeneration of propylene with various comonomer based adhesives. However,such adhesives typically have long set-time. For fast throughput,packaging manufacturers desire adhesives with short set-time.

To increase throughput, a nucleator is added to polypropylene-based hotmelt adhesive to speed the crystallization time (set-time) inUS2005/0288412. However, the drawback to this approach is that the heatresistance of the adhesive can also decrease.

There is a need in the art for a hot melt adhesive that possesses goodhigh heat resistance and fast set-time performances. The currentinvention fulfills this need.

BRIEF SUMMARY OF THE INVENTION

The invention provides novel adhesives, methods of using the adhesivesto bond substrates together, and to articles of manufacture comprisingthe adhesives.

In one embodiment, the adhesive of the present invention comprises (a) apolymer component which contains in polymerized form at least 65 wt % ofpropylene, based on the total weight of the polymer component; (b) atleast one nucleator; and (c) at least one functionalized wax, whereinthe weight ratio of the nucleator to the functionalized wax ranges fromabout 1:500 to about 50:1. The nucleator can be selected from organicacid salts, phosphoric acids, ethylene-(meth)acrylic acid ionomers,multiple amides components, dibenzylidenesorbitols, sugar alcohols andcorresponding derivatives thereof. The functionalized wax can beselected from unsaturated carboxylic acid or anhydride grafted waxes. Ina further embodiment, the functionalized wax is a maleic anhydridegrafted polypropylene.

Another aspect of the invention is directed to an adhesive comprising(i) at least one polymer component which contains in polymerized form atleast 65 wt % propylene, based on the total weight of the polymercomponent; (ii) at least one nucleator selected from the groupconsisting of organic acid salts, phosphoric acids,ethylene-(meth)acrylic acid ionomers, multi amides components, sorbitolsand their corresponding derivatives thereof; and (iii) at least onefunctionalized wax which is a wax grafted with at least one olefinicallyunsaturated dicarboxylic anhydride of less than 12 carbon atoms.

In another aspect, the invention is directed to an adhesive comprising(1) from about 30 to about 99 wt %, based on the total weight of theadhesive, of a polymer component, which contains in polymerized form atleast 65 wt % of propylene, based on the total weight of the polymercomponent; (2) from about 0.05 to about 1 wt %, based on the totalweight of the adhesive, of at least one nucleator; and (3) from about0.01 to about 5.0 wt % based on the total weight of the adhesive, of atleast one functionalized wax, wherein the total wt % of the adhesiveequals to 100 wt %.

In one embodiment of the present invention the polymer component is asingle polymer or a blend of polymers. The polymer component cancomprise at least one copolymer of propylene and at least one comonomerselected from ethylene and/or C₄₋₂₀ alpha-olefins, wherein the copolymerpreferably contains in polymerized form at least 65 wt %, morepreferably at least 80 wt % of propylene and/or preferably contains nomore than 35 wt %, more preferably no more than 20 wt % of ethyleneand/or C₄₋₂₀ alpha-olefins, each based on the total weight of thecopolymer.

In a further aspect, the adhesives of the invention are hot meltadhesives.

In another embodiment, the adhesives of the invention further compriseoils, tackifiers, non-functionalized waxes, plasticizers, and/orstabilizers, and/or mixtures thereof.

Another aspect is directed to a process for forming adhesives with highheat resistance and fast set-time comprising heating a polymer componentwhich contains in polymerized form at least 65 wt % of propylene, basedon the total weight of the polymer component, to its molten state;adding at least one nucleator and at least one functionalized wax to themolten polymer component until a homogenous mixture is formed; andcooling the mixture, preferably to room temperature (22° C.). The cooledadhesive can be pelletized or formed into blocks for storage orshipping. The adhesive can be reheated to apply onto substrates.

A further embodiment is directed to applying the adhesive describedherein. The adhesive is applied in a molten state onto a substrate;placing another substrate onto the molten adhesive; cooling the adhesivethereby forming a bond of two substrates.

Yet another aspect of the invention is directed to articles ofmanufacture comprising the adhesives described herein. Articles ofmanufacture encompassed by the invention include cases, cartons andtrays.

BRIEF SUMMARY OF THE FIGURES

FIGS. 1-3 are diagrams illustrating placement of the adhesive bead andother dimensional parameters used to measure the heat resistance of anadhesive bond.

FIGS. 4-7 are microscopic photographs of spherulites in adhesiveformulations with 1000× magnification and cross-polarized light.

FIG. 8 is a DSC curve of Epolene E43.

DETAILED DESCRIPTION OF THE INVENTION

All documents cited herein are incorporated in their entireties byreference.

The term “polymer component” as used herein, refers to a single(co)polymer or a blend of different (co)polymers, wherein the combinedtotal of all units derived from propylene in all (co)polymers of thepolymer component is at least 65 wt %, based on the total weight of thepolymer component. The term (co)polymer, as used herein, refers topolypropylene homopolymers or copolymers of propylene and comonomersselected from ethylene and/or C₄₋₂₀ alpha olefins.

The polymer component may comprise a copolymer of propylene and at leastone comonomer selected from ethylene or C₄₋₂₀ alpha-olefins. Preferredpolymer for the practice of this invention typically comprises unitsderived from propylene in an amount of at least 65 wt %, preferably atleast about 80 wt % and more preferably at least 85 wt % of thecopolymer. The typical amount of units derived from ethylene comonomeris preferably at least 1 wt %, more preferably at least 2 wt % andparticularly preferably at least 4 wt %, and the maximum amount of unitsderived from ethylene present in these copolymers is preferably not inexcess of 35 wt %, more preferably not in excess of 30 wt % andparticularly preferably not in excess of 20 wt % of the copolymer. Theamount of units derived from the C₄₋₂₀ alpha-olefins described above, ifpresent, is preferably at least 1 wt %, more preferably at least 2 wt %and particularly preferably at least about 4 wt %, and the typicalmaximum amount of units derived from C₄₋₂₀ alpha-olefins describedabove, preferably does not exceed 35 wt %, more preferably it does notexceed 30 wt % and particularly preferably it does not exceed 20 wt % ofthe copolymer. The combined total of units derived from ethylene and anyC₄₋₂₀ alpha-olefin preferably does not exceed 35 wt %, more preferablyit does not exceed 30 wt %, and particularly preferably it does notexceed about 20 wt % of the copolymer.

The polymer component may comprise at least one semi-crystallinepolypropylene (co)polymer. The term “polypropylene (co)polymer,” as usedherein, refers to a polypropylene homopolymer or a copolymer, at whichcontains in polymerized form at least 65 wt % of propylene, based on thetotal weight of the polypropylene (co)polymer.

The term “semi-crystalline” used for the polypropylene polymer refers tothose polymeric materials that contain both crystalline and amorphousregions in the solid state. In the crystalline region, the molecularchains of the polymers are all arranged in ordered three-dimensionalarrays whose structure can be fully characterized by their unit cells,the smallest structural unit used to describe a crystal. The amorphouspolymers, in contrast, do not have ordered three-dimensional structuresin the solid state. Their molecular chains are arranged in a completelyrandom fashion in space. Semi-crystalline polymers can be easilydistinguished from completely amorphous polymers by observing thepresence or absence of a melting point (Tm) and the associated enthalpyor heat of melting (ΔHm) derived from the transformation of thecrystalline state to liquid state upon heating. All semi-crystallinepolymers exhibit a melting point, whereas the melting point is absentfor amorphous polymers. Amorphous polymers undergo a transition from aglassy solid to a rubbery elastic state in a narrow temperature rangearound a glass transition temperature Tg. One should not confuse theglass transition temperature Tg with the melting point Tm. Unlike themelting transition of the crystalline materials, the glass transition ofamorphous polymers do not have an enthalpy change (OH) associated withit.

It should be understood that semi-crystalline polypropylene polymersdefined above are often referred to as crystalline polymers in thetrade. Except for the single crystals prepared in the laboratories on asmall scale, perfect crystalline polymers are not encountered in thecommercial world and all so-called crystalline polymers, strictlyspeaking, are semi-crystalline. The definition of semi-crystallinepolymers set forth herein, therefore, also includes “crystallinepolypropylene polymers”.

Since semi-crystalline polypropylene polymers contain both crystallineand amorphous regions, in addition to melting transition of crystals,they can exhibit a glass transition associated with the amorphous regionof the material. The glass transition takes place at a temperature belowthe melting point.

The term “semi-crystalline polypropylene polymer” as used in the presentinvention refers to polypropylene polymers having a heat of melting, asdetermined by DSC, of at least about 30 J/g, preferably at least about40 J/g, and more preferably at least about 50 J/g. The term “heat ofmelting” as used herein, refers to the energy absorbed in converting amaterial from a crystalline or semi-crystalline state to an amorphousstate, and this value can be determined by various analytical methods,including ISO 11357-3. Unless otherwise stated, all reported heat ofmelting values are determined in accordance with ISO 11357-3, with minoradjustments as indicated in the experimental section.

The semi-crystalline polypropylene polymers of the type described abovecan be purchased from numerous commercial sources, for example,polypropylene-based semi-crystalline polypropylene polymers, amongothers, from Lyondell Basell, Ineos, Borealis, TVK and Exxon Mobil.

In one embodiment of the invention, the polymer component is a polymerblend which comprises at least one semi-crystalline polypropylenepolymer and at least one elastomeric rubber. Elastomeric rubber,elastomer, and elastomeric polymer are synonymous terms. These materialsare either entirely amorphous or of very low crystallinity, preferablywith a heat of melting of <30 J/g, more preferably <20 J/g, and mostpreferably <10 J/g, as determined in accordance with ISO 11357-3. Theterm “elastomeric rubber” reflects the property of the material that itcan undergo a substantial elongation and then returned to itsapproximately original dimensions upon release of the stress elongatingthe material. Preferably elastomeric rubber of the present inventionwill have less than 50%, such as less than 30% or less than 10%permanent set after one minute when recovering from a strain of 100%applied for one minute at a temperature of 22° C. The elastomeric rubberof the present invention can be selected from ethylene-propylene rubbers(EPR) and/or ethylene-propylene diene rubbers (EPDM). The polymer blendalso contains in polymerized form at least 65 wt %, more preferably atleast 80 wt % of propylene and/or preferably contains in polymerizedform no more than 35 wt %, more preferably no more than 20 wt % ofethylene and/or C₄₋₂₀ alpha-olefins. Preferably, each of the polymers inthe polymer blend also contains in polymerized form at least 65 wt %,more preferably at least 80 wt % of propylene and/or preferably containsin polymerized no more than 35 wt %, more preferably no more than 20percent by weight of ethylene and/or C₄₋₂₀ alpha-olefins.

Preferred ethylene-propylene rubber (EPR) of the present inventioncomprise from 10 to 35 wt % of ethylene and from 65 to 90 wt % ofpropylene

The elastomeric rubber and the semi-crystalline polypropylene(co)polymer can be pre-mixed to form a polymer blend or polymer alloy.The polymer blend can be prepared by mechanical mixing of EPR/EPDMrubber with a semi-crystalline polypropylene polymer through an extruderor Banbury Mixer or the like.

The polymer or the polymer blend component preferably exhibits a heat ofmelting (Tm) of less than or equal to about 95 J/g. The heat of meltingis the quantity of heat needed to melt a unit mass of a solid at aconstant temperature, and this is determined Differential Scanningcalorimetry (DSC) in accordance with ISO 11357-3.

The polymer or the polymer blend component preferably exhibits arecrystallization temperature of less than about 110° C., preferablyless than about 95° C. The recrystallization temperature is thetemperature at which random molecular configuration of the melt becomesan ordered, crystalline structure. This temperature can also bedetermined by a DSC. Depending on the crystallinity of the polymer orthe polymer blend, the recrystallization temperature varies.

The polymer blend can also be made in situ by step-wise polymerizationin a single or a series of parallel reactors. An example of such in situreactor process is the Catalloy Process employed by LyondellBasell. Thisprocess utilizes multiple gas phase reactors in parallel that allowseparate polymerization of different monomer feed stock in each reactor.Each reactor runs independently of the others so each reactor productcan be quite dissimilar to what is produced in the other reactors. Theproduct from each reactor can be mixed or blended, creating alloyedpolymers directly from the polymerization process. The describedmulti-stage polymerization process is for example disclosed in thefollowing published references: EP-A-0 472 946, EP-A-0 477 662, EP-A-0483 675 and EP-A-0 489 284.

An example of polymer blends or alloys produced by the Catalloy Processare thermoplastic olefins (TPOs), which are blends or alloys of EPR andsemi-crystalline polypropylene (co)polymers. Blends or alloys producedby the Catalloy Process are commercially available from LyondellBasellunder the trade name designation Adflex, Softell, and Hifax.

The polymer component of the present invention can also comprise atleast one thermomechanical degraded semi-crystalline polypropylene(co)polymer or a blend of at least one thermomechanical degradedsemi-crystalline polypropylene polymer and at least one thermomechanicaldegraded elastomeric rubber. Preferably the polymer component is athermomechanical degraded blend of at least two polymers where eachpolymer contains at least 65 wt %, more preferably at least 80 wt % ofpropylene and/or preferably contains in polymerized form no more than 35wt %, more preferably no more than 20 wt % of ethylene and/or C₄₋₂₀alpha-olefins.

In the context of the present invention, the term “thermomechanicaldegraded semi-crystalline polypropylene polymer” and “thermomechanicaldegraded elastomeric rubber” is understood to mean a polymer that ismanufactured from the corresponding polymer by thermomechanicaldegradation under shear stress, preferably in an extruder. Here, theweight average molecular weight (M_(w)) of the degraded polymer measuredunder comparable conditions is always smaller than the weight averagemolecular weight (M_(w)) of the un-degraded polymer.

In the context of the present invention, the term “thermomechanicaldegradation” is understood to mean the polymer chain shortening andmolecular weight reducing degradation process of a polymer which occursin an extruder under the action of heat and shear stress. In order toincrease the efficiency of the thermomechanical degradation it isparticularly advantageous to carry out the thermomechanical degradationin the presence of at least one radical donor and/or in the presence ofoxygen.

In the context of the present invention, the term “extruder” canpreferably be understood to mean both single-screw as well as twin-screwextruders. The latter is technically more complex and are available invarious types. One differentiates between co- and counter-rotating,intermeshing or tangential, longitudinal or transverse, open or closedand cylindrical or conical models. Compounders, expansion extruders orplanetary extruders can also be used. Preferably, at least onetwin-screw extruder is used for the process according to the invention.

The polymer blend of the present invention preferably comprisespolymers, such as semi-crystalline polypropylene (co)polymers, whichhave a melt viscosity, measured at 200° C., preferably between 300 mPa·sand 1,000,000 mPa·s, particularly preferably between 300 mPa·s and500,000 mPa·s, more preferably between 300 mPa·s and 250,000 mPa·s andquite particularly preferably between 300 mPa·s and 150,000 mPa·s. Themelt viscosity in mPa·s can be measured with a Brookfield Thermosel RVTviscometer (available from Brookfield Engineering Laboratories, Inc.,Stoughton, Mass. USA) at the temperature given. For viscosities up to100,000 mPa·s spindle 27 was used; higher viscosities were measured withspindle 29. The rotational speed of the chosen spindle is preferablyadjusted in a way that the torque readings are in the range of 10 to95%, more preferably about 50%.

The polymer component is present in an amount of from about 30 wt % toabout 99 wt %, more preferably from about 50 wt % to about 99 wt %, andeven more preferably from about 60 wt % to about 99 wt %, based on thetotal weight of the adhesive.

It has been discovered that hot melt adhesives with high heat resistanceand fast set-time can be prepared by combining at least one nucleatorand at least one functionalized wax in an adhesive, comprising a polymercomponent. The nucleator and the functionalized wax in the adhesive worktogether to produce results not obtained by them independently. Thissynergistic effect allows for higher heat resistance and fast set timeof the adhesive. The adhesives of the present invention also comprise atleast one nucleator component. It is common in the art to use theterminology “nucleator” to include nucleating agents or clarifyingagents. Nucleator, when incorporated in a polymer, forms nuclei forcrystal growth, also known as spherulites, in the polymer melt.Spherulites are rounded aggregate of crystal structures with spheruletextures, occurred by growing of lamellae with specific arrangement fromcrystal nucleus, and are observed by optical microscopy and crosspolarized light. Nucleators have typically been used to increase theprocessing speed in injection molding and extrusion process. Descriptionand suitable examples of nucleators are found in Nucleating Agents byStuart Fairgrieve, Woodhead Publishing Limited, November 2007.

Suitable nucleators are, for example, salts of organic acids, such asaliphatic monocarboxylic or dicarboxylic acids, examples being alkalimetal, alkaline earth metal or aluminum salts of succinic acid, glutaricacid, caproic acid, montanic acid or corresponding salts of carboxylicacids containing aromatic groups, such as benzoic, alkylbenzoic,naphthoic, phenylacetic or cinnamic acid. Also suitable are adjuvantsbased on phosphoric acid, examples being alkali metal organophosphates.Also effective are ethylene-(meth)acrylic acid ionomers, examples beingcorresponding commercial products such as the grades from the Aclyn®range (commercial products from Honeywell) or from the Surlyn® range(commercial products from Dupont). Multiple amides components and theirderivatives are also suitable as nucleators. Multiple amides componentsare compounds which have at least two amide functionalities on anaromatic or aliphatic core groups. Examples include aromatic tris amidederivatives such as 1,3,5-benzenetrisamide,N,N,N-tris-tert-butyl-1,3,5-benzenetricarboxamide,N,N,N-tris-cyclohexyl-1,3,5-benzenetricarboxamide,N,N,N-n-butyl-1,3,5-benzene-tricarboxamide,N,N,N-tris-isopropyl-1,3,5-benzenetricarboxamide, and the like, whichare described in Frank Abraham et. al., Synthesis andStructure—Efficiency Relations of 1,3,5-Benzenetrisamides as NucleatingAgents and Clarifiers for Isotactic Poly(propylene), Macromol. Chem.Phys. 2010, 211, 171-181 and JINGBO WANG, et. al., Crystal Structure andin Morphologies of Polypropylene Homopolymer and Propylene-EthyleneRandom Copolymer: Effect of the Substituted 1,3,5-Benzenetrisamides,Journal of Polymer Science: Part B: Polymer Physics, Vol. 46, 1067-1078(2008). Aromatic tris amides are also commercially available asIrgaclear XT 386 and NJSTAR NU-100(N,N′-dicyclohexyl-2,6-naphthalenendicarboxamide). Multiple amidescomponents also includes aliphatic tris amides derivatives such asN,N′,N″-tris(2-methylcyclohexyl)-1,2,3-propanetricarboxamide, availableas RiKACLEAR PC1, and the like. Likewise, suitable aredibenzylidenesorbitol type, not only in the unsubstituted form but alsoin the singly or multiply alkyl-substituted form, methyl-substituted forexample. Another suitable class of nucleators includes sugars or sugaralcohols of allose, altrose, fructose, galactose, glucose, gulose,idose, mannose, sorbose, talose, tagatose, arabinose, ribose, ribulose,xylose, xylulose, lyxose, erythrose, threose sorbitol, and xylitol. In apreferred embodiment, the nucleator is a clarifying agent. A Clarifyingagent is typically an organic, non-polymeric molecule that increases thepolymer transparency by reducing the size of the polymer spherulites.Suitable clarifying agents include sorbitol derivatives, for example,1,3:2,4 dibenzylidene sorbitol, 1,2,3,4-di-para-methylbenzylidenesorbitol, 1,2,3,4-di-meta, para-methylbenzylidene sorbitol,bis(4-propylbenzylidene) propyl sorbitol and mixtures thereof. Theaforementioned clarifying agents are commercially available fromMilliken Chemical under the trade names Millad and Hyperform HPN series.

Preferably, the nucleator or a mixture of different nucleator is presentfrom about 0.01 wt % to less than about 3 wt %, preferably less thanabout 1 wt %, based on the total weight of the adhesive.

The adhesive further comprises a functionalized wax or a mixture offunctionalized waxes.

The term “wax” means a polymeric material that has a heat of meltinggreater than 50 J/g. Generally, heat of melting of the wax component ishigher than the heat of melting of the polymer or polymer blendcomponent. While some waxes and some polymers (and polymer blends) haveoverlapping heat of melting values, the wax, for this purpose of thisinvention, has a higher heat of melting value than the polymer or thepolymer blend, as defined above. Typically, the difference between thewax and the polymer or polymer blend is greater than about 10 J/g,preferably greater than about 15 J/g. Also, the wax component has arecrystallization temperature greater than about 95° C., preferablygreater than about 100° C. Recrystallization temperature, as usedherein, refers to the temperature of maximum heat evolution from thesample as it is cooled at a controlled rate, and this value can bedetermined by various analytical methods, including ISO 11357-3. Unlessotherwise noted, all recrystallization temperature values are determinedin accordance with ISO 11357-3, with minor adjustments as indicated inthe experimental section. Again, while some waxes and some polymers (andpolymer blends) have overlapping recrystallization temperature, the wax,for this purpose of this invention, has a recrystallization temperaturethat is greater than the polymer or the polymer blend.

The term “functionalized wax” refers to a wax which comprises at leastone functional group that has been grafted onto, copolymerized oroxidized in an amount of at least 0.01 wt %, preferably of at least 0.1wt %, and more preferably of at least 0.5 wt %, and up to 5 wt %, eachbased on the total amount of the functionalized wax.

In one embodiment, the wax is grafted with an unsaturated carboxylicacid or its anhydride. Representative examples of suitable waxes includehomopolymers and copolymers of various olefins such as ethylene,propylene, butylene, pentene, hexylene, heptene and octene. Suitablemonomers for grafting onto the aforementioned polyolefin are, forexample, olefinically unsaturated monocarboxylic acids of less than 12carbon atoms, e.g., acrylic acid or methacrylic acid, and thecorresponding tert-butyl esters, e.g., tert-butyl(meth)acrylate,olefinically unsaturated dicarboxylic acids of less than 12 carbonatoms, e.g., crotonic acid, fumaric acid, maleic acid, and itaconic acidand the corresponding mono- and/or di-tert-butyl esters, e.g., mono- ordi-tert-butyl crotonate, mono- or di-tert-butyl fumarate and mono- ordi-tert-butyl maleate, olefinically unsaturated dicarboxylic anhydridesof less than 12 carbon atoms, e.g., maleic anhydride, sulfo- orsulfonyl-containing olefinically unsaturated monomers of less than 12carbon atoms, e.g., p-styrenesulfonic acid,2-(meth)acrylamide-2-methylpropenesulfonic acid or2sulfonyl(meth)acrylate, oxazolinyl-containing olefinically unsaturatedmonomers of less than 12 carbon atoms, e.g., vinyloxazolines andvinyloxazoline derivatives, and epoxy-containing olefinicallyunsaturated monomers of less than 12 carbon atoms, e.g.,glycidyl(meth)acrylate or allyl glycidyl ether. The acid number of thegrafted wax is present from about 5 to about 200 mg KOH/g, preferablyfrom about 10 to about 100 mg/KOH, measured in accordance with ASTMD-1386.

In one exemplary embodiment, the functionalized wax used in the practiceof the invention is a maleic anhydride grafted on a polypropylene wax. Avariety of maleic anhydride grafted wax suitable for use herein areavailable commercially and/or are obtainable using known procedures. Forexample, maleated polyethylenes are available from Honeywell under thetrade names A-C 575 and A-C 573, and from DuPont as products listed aspart of their Fusabond E series. Maleated polypropylenes are availablefrom Honeywell under the trade names A-C 597A, A-C 597P, A-C 907P, A-C596A, A-C 596P, A-C 950P and A-C 1325P, from DuPont as products listedunder the Fusabond P trade named series, from Eastman under the tradenames G-3015, G-3003, and from Westlake under the trade name EPOLENEE-43. Any known procedures for producing maleated polyolefins fromprecursor compounds can be adapted for use to make starting materialssuitable for use herein. For example, U.S. Pat. No. 7,256,236,incorporated herein by reference, discloses certain preferred methodsfor producing maleated polypropylenes suitable for use herein.

In another embodiment, the functionalized wax is a wax that has beencopolymerized with a functional group. Representative examples ofsuitable copolymerizes waxes include terpolymer of ethylene-acrylicester-maleic anhydride and ethylene-acrylic ester-glycidyl methacrylate,available as Lotader® MAH and Lotader® GMA, respectively.

In a further embodiment, the functionalized wax is an oxidizedpolyethylene homopolymers, including high density oxidized polyethylenehomopolymers. Exemplary oxidized polyethylenes are available fromHoneywell under the trade names A-C 673P, A-C 680, A-C 655, A-C 629, A-C629A, A-C 656, A-C 6702, A-C 307, A-C 307A, A-C 316, A-C316A, A-C 325,A-C 392, A-C 330, A-C 395 and A-C 395A.

The functionalized wax may be present from about 0.1 wt % to about 15 wt%, preferably from about 1 wt % to about 5 wt %, based on the totalweight of the adhesive. Preferably the functionalized wax is a propylenefunctionalized with maleic anhydride wherein the acid number of thegrafted wax is present from about 5 to about 200 mg KOH/g, preferablyfrom about 10 to about 100 mg KOH/g, measured in accordance with ASTMD-1386.

While not bound by any particular theory, it is believed that thecombined effect of the nucleator and the functionalized wax results in asynergy of producing a multitude of spherulites with a large totalsurface area. The increased surface area increases the energy requiredto disrupt the structure and integrity of the hot melt adhesive, thus,the performance of the heat resistance increases.

The ratio of the nucleator and the functionalized wax in an adhesivecomposition should be in the ratio of about 1:500 to about 50:1,preferably, from about 1:100 to about 10:1, and more preferably fromabout 1:40 to about 2:1. Adhesive compositions with ratio of nucleatorand functionalized wax outside this range results in poor performance,e.g., poor heat resistance and poor set time.

The adhesives of the invention may optionally comprise tackifiers,non-functionalized waxes, plasticizers, stabilizers, additives ormixtures thereof.

The tackifier component may typically be present up to about 60 wt %,more preferably up to about 50 wt %, even more preferably up to about 40wt %, based on the total weight of the adhesive.

Typical tackifier has a Ring and Ball softening points, as determined byASTM method E28, of about 70° C. to about 150° C., more preferably ofabout 95° C. to about 130° C.

Useful tackifying resins may include any compatible resin or mixturesthereof such as natural and modified rosins including, for example, asgum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenatedrosin, dimerized rosin, resinates, and polymerized rosin; glycerol andpentaerythritol esters of natural and modified rosins, including, forexample as the glycerol ester of pale, wood rosin, the glycerol ester ofhydrogenated rosin, the glycerol ester of polymerized rosin, thepentaerythritol ester of hydrogenated rosin, and the phenolic-modifiedpentaerythritol ester of rosin; copolymers and terpolymers of naturedterpenes, including, for example, styrene/terpene and alpha methylstyrene/terpene; polyterpene resins having a softening point, asdetermined by ASTM method E28, of from about 70° C. to 150° C.; phenolicmodified terpene resins and hydrogenated derivatives thereof including,for example, the resin product resulting from the condensation, in anacidic medium, of a bicyclic terpene and a phenol; aliphatic petroleumhydrocarbon resins having a Ball and Ring softening point of from about70° C. to 135° C.; aromatic petroleum hydrocarbon resins and thehydrogenated derivatives thereof; and alicyclic petroleum hydrocarbonresins and the hydrogenated derivatives thereof. Examples ofhydrogenated tackifiers particularly suitable include Escorez 5400 fromExxon Mobil Chemicals, Arkon P100 from Arakawa and Regalite S1100 fromEastman Chemical, and the like. Also included are the cyclic or acyclicC₅ resins and aromatic modified acyclic or cyclic resins. Examples ofcommercially available rosins and rosin derivatives that could be usedto practice the invention include SYLVALITE RE 110L, SYLVARES RE 115,and SYLVARES RE 104 available from Arizona Chemical; Dertocal 140 fromDRT; Limed Rosin No. 1, GB-120, and Pencel C from Arakawa Chemical.Examples of commercially available phenolic modified terpene resins areSylvares TP 2040 HM and Sylvares TP 300, both available from ArizonaChemical.

Preferred tackifiers are synthetic hydrocarbon resins. Included arealiphatic or cycloaliphatic hydrocarbons, aromatic hydrocarbons,aromatically modified aliphatic or cycloaliphatic hydrocarbons andmixtures thereof.

Non-limiting examples include aliphatic olefin derived resins such asthose available from Goodyear under the Wingtack® Extra trade name andthe Escorez® 1300 series from Exxon. A common C₅ tackifying resin inthis class is a diene-olefin copolymer of piperylene and2-methyl-2-butene having a softening point of about 95° C. This resin isavailable commercially under the trade name Wingtack 95. Eastotac seriesfrom Eastman are also useful in the invention.

Also useful are aromatic hydrocarbon resins that are C₉aromatic/aliphatic olefin-derived and available from Sartomer and CrayValley under the trade name Norsolene and from Rutgers series of TKaromatic hydrocarbon resins. Norsolene M1090 is a low molecular weightthermoplastic hydrocarbon polymer having a Ring and Ball softening pointof 95-105° C. and is commercially available from Cray Valley.

Alpha methyl styrene such as Kristalex 3085 and 3100 from EastmanChemicals, Sylvares SA 100 from Arizona chemicals are also useful astackifiers in the invention. Adhesives formulated with such alpha methylstyrenes have resultant viscosity of less than about 1500 mPa·s at 121°C. Mixtures of two or more described tackifying resins may be requiredfor some formulations.

Small quantities of alkyl phenolic tackifiers can be blended withadditional tackifier agents detailed above to improve the hightemperature performance of these adhesives. Alkyl phenolics added inless than 20 wt % of the total weight of the adhesive are compatible andin the proper combination increase high temperature adhesiveperformance. Alkyl phenolics are commercially available from ArakawaChemical under the Tamanol trade name and in several product lines fromSchenectady International.

The adhesive of the invention may optionally comprise anon-functionalized wax. Non-functional waxes suitable for use in thepresent invention include paraffin waxes, microcrystalline waxes,polyethylene waxes, polypropylene waxes, by-product polyethylene waxes,Fischer-Tropsch waxes, oxidized Fischer-Tropsch waxes and functionalizedwaxes such as hydroxy stearamide waxes and fatty amide waxes. Highdensity low molecular weight polyethylene waxes, by-product polyethylenewaxes and Fischer-Tropsch waxes are conventionally referred to in theart as synthetic high melting point waxes.

Paraffin waxes that can be used in the practice of the invention includePacemaker® 30, 32, 35, 37, 40, 42, 45 & 53 available from CitgoPetroleum, Co.; Astor Okerin® 236 available from Honeywell; R-7152Paraffin Wax available from Moore & Munger; R-2540 available from Mooreand Munger; and other paraffinic waxes such as those available fromSasol Wax under the product designations Sasolwax 5603, 6203 and 6805

The microcrystalline waxes useful here are those having 50 percent byweight or more cyclo or branched alkanes with a length of between 30 and100 carbons. They are generally less crystalline than paraffin andpolyethylene waxes, and have melting points of greater than about 70° C.Examples include Victory® Amber Wax, a 70° C. melting point waxavailable from Baker Petrolite Corp.; Bareco® ES-796 Amber Wax, a 70° C.melt point wax available from Bareco; Besquare® 175 and 195 Amber Waxesand 80° C. and 90° C. melt point microcrystalline waxes both availablefrom Baker Petrolite Corp.; Indramic® 91, a 90° C. melt point waxavailable from Industrial Raw Materials; and Petrowax® 9508 Light, a 90°C. melt point wax available from Petrowax. Other examples ofmicrocrystalline waxes are Sasolwax 3971 available from Sasol Wax andMicrowax K4001 available from Alfred Kochem GmBH.

Exemplary high density low molecular weight polyethylene waxes fallingwithin this category include ethylene homopolymers available from BackerPetrolite Corp. as Polywax™ 500, Polywax™ 1500 and Polywax™ 2000.Polywax™ 2000 has a molecular weight of approximately 2000, an Mw/Mn ofapproximately 1.0, a density at 16° C. of about 0.97 g/cm³, and amelting point of approximately 126° C.

When used, the non-functionalized wax component will typically bepresent in amounts of up to about 45 wt %. Formulation comprising a waxcomponent will more typically comprise from about 5 to about 40 wt %.Preferred waxes have a melt temperature between 49° C. and 121° C., morepreferably between 66° C. and 110° C., and most preferable between 82°C. and 104° C.

The adhesives of the present invention may desirably also contain aplasticizer, including oil. Suitable plasticizers include polybutenes,phthalates, benzoates, adipic esters and the like. Particularlypreferred plasticizers include phthalates such as di-iso-undecylphthalate (DIUP), di-iso-nonylphthalate (DINP), dioctylphthalates (DOP),mineral oil, aliphatic oils, olefin oligomers and low molecular weightpolymers, vegetable oil, animal oils and derivatives. Preferredplasticizers include paraffinic oil, naphthenic oil, aromatic oil, longchain partial ether ester, alkyl monoesters, epoxidized oils, dialkyldiesters, aromatic diesters, alkyl ether monoester and mixtures thereof.

In one embodiment, the oil is typically present at about 1 to about 30wt %, more preferably 5 to 20 wt %, based on the total weight of theadhesive. In some embodiments, however, oils may not be desired and ispresent at less than 5 wt %, preferably less than 3 wt %, morepreferably less than 1 wt %, more preferably less than 0.5 wt % or evenessentially free of oil, based upon the total weight of the adhesive.

The adhesives of the present invention may desirably also contain atleast one stabilizer and/or at least one antioxidant. These compoundsare added to protect the adhesive from degradation caused by reactionwith oxygen induced by such things as heat, light, or residual catalystfrom the raw materials such as the tackifying resin.

Among the applicable stabilizers or antioxidants included herein arehigh molecular weight hindered phenols and multifunctional phenols suchas sulfur and phosphorous-containing phenol. Hindered phenols are wellknown to those skilled in the art and may be characterized as phenoliccompounds which also contain sterically bulky radicals in closeproximity to the phenolic hydroxyl group thereof. In particular,tertiary butyl groups generally are substituted onto the benzene ring inat least one of the ortho positions relative to the phenolic hydroxylgroup. The presence of these sterically bulky substituted radicals inthe vicinity of the hydroxyl group serves to retard its stretchingfrequency, and correspondingly, its reactivity; this hindrance thusproviding the phenolic compound with its stabilizing properties.Representative hindered phenols include;1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-benzene;pentaerythrityl tetrakis-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate;n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate;4,4′-methylenebis(2,6-tert-butyl-phenol);4,4′-thiobis(6-tert-butyl-o-cresol); 2,6-di-tertbutylphenol;6-(4-hydroxyphenoxy)-2,4-bis(n-octyl-thio)-1,3,5 triazine;di-n-octylthio)ethyl 3,5-di-tert-butyl-4-hydroxy-benzoate; and sorbitolhexa[3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-propionate].

Such antioxidants are commercially available from Ciba SpecialtyChemicals and include Irganox® 565, 1010, 1076 and 1726 which arehindered phenols. These are primary antioxidants which act as radicalscavengers and may be used alone or in combination with otherantioxidants such as phosphite antioxidants like Irgafos® 168 availablefrom Ciba Specialty Chemicals. Phosphite catalysts are consideredsecondary catalysts and are not generally used alone. These areprimarily used as peroxide decomposers. Other available catalysts areCyanox® LTDP available from Cytec Industries and Ethanox® 330 availablefrom Albemarle Corp. Many such antioxidants are available either to beused alone or in combination with other such antioxidants. Thesecompounds are added to the hot melts in small amounts, typically lessthan about 10 wt %, and have no effect on other physical properties.Other compounds that could be added that also do not affect physicalproperties are pigments which add color, or fluorescing agents, tomention only a couple. Additives like these are known to those skilledin the art.

Depending on the contemplated end uses of the adhesives, other additivessuch as pigments, dyestuffs and fillers conventionally added to hot meltadhesives may be incorporated in minor amounts, i.e., up to about 10% byweight, into the formulations of the present invention.

In one embodiment of the invention, a method of increasing the heatresistance of a hot melt adhesive composition is provided. The methodcomprises adding at least one nucleator and at least one functionalizedwax in a polymer component, preferably comprising at least onecrystalline or semi-crystalline polypropylene (co)polymer to increasethe heat resistance of the composition. The method of the invention canbe used to increase the heat resistance of a hot melt adhesiveformulation at least by 5° C. or more. Formulations showing an increasein heat resistance of least 5° C., at least 10° C., more preferably atleast 15° C. or more can be achieved in accordance with the practice ofthe invention. The adhesives may desirably be formulated forconventional and low temperatures application, i.e., formulations thatcan be applied at temperatures at about 177° C. (350° F.) and down toabout 93° C. (200° F.). They provide superior adhesive bonds even whenexposed to a wide variety of temperature conditions. The adhesivespossess excellent heat resistance and fast set-time.

The adhesive compositions of the present invention are prepared byblending the components in a melt at a temperature above about 180° C.to form a homogeneous blend. Various methods of blending are known inthe art and any method that produces a homogeneous blend, includingextrusion process, is satisfactory. The blend is then cooled and may beformed into pellets or blocks for storage or shipping. These pre-formedadhesives can then be reheated to apply onto substrates.

In one embodiment of the present invention the adhesive comprises

-   -   (a) from about 30 to about 99 wt % of at least one polymer        component which contains in polymerized form of at least 65 wt %        propylene, based on the total weight of the polymer component;    -   (b) from about 0.01 to about 3 wt %, based on the weight of the        adhesive, of at least one nucleator;    -   (c) from about 0.1 to about 15 wt %, based on the weight of the        adhesive, at least one functionalized wax;    -   (d) from 0 to about 60 wt %, based on the weight of the        adhesive, of at least one tackifier; and    -   (e) from 0 to about 5 wt %, based on the weight of the adhesive,        of at least one antioxidant;    -   wherein the weight ratio of the nucleator to the functionalized        wax ranges from about 1:500 to about 50:1.

In another embodiment of the present invention the adhesive comprises

-   -   (i) from about 30 to about 99 wt % of at least one polymer        component which contains in polymerized form of at least 65 wt %        of propylene, based on the total weight of the polymer        component;    -   (ii) from about 0.01 to about 3 wt %, based on the weight of the        adhesive, of at least one nucleator selected form the group        consisting of organic acid salts, phosphoric acids,        ethylene-(meth)acrylic acid ionomers, multiple amides        components, sorbitols and their corresponding derivatives        thereof; and    -   (iii) from about 0.1 to about 15 wt %, based on the weight of        the adhesive, of at least one functionalized wax which is a wax        grafted with at least one olefinically unsaturated dicarboxylic        anhydride of less than 12 carbon atoms;    -   (iv) from 0 to about 60 wt % of at least one tackifier; and    -   (v) from 0 to about 5 wt % of at least one antioxidant.

Yet in another embodiment of the invention, the adhesive comprise

-   -   (1) from about 30 to about 99 wt % of a polymer component which        contains in polymerized form of at least 65 wt % of propylene,        based on the total weight of the polymer component;    -   (2) from about 0.05 to about 1 wt %, based on the weight of the        adhesive, of at least one nucleator; and    -   (3) from about 0.01 to about 5 wt %, based on the weight of the        adhesive, of at least one functionalized wax;    -   wherein the total weight percent of the adhesive equals to 100        weight percent.

In another embodiment of the invention, a method for bonding a substrateto a similar or dissimilar substrate is provided. The method comprisesapplying to at least a first substrate a molten adhesive of the presentinvention, bringing a second substrate in contact with the adhesiveapplied to the first substrate, and allowing the composition tosolidify, thereby the first and second substrates are bonded together,wherein the adhesive of the present invention preferably comprises atleast one crystalline or semi-crystalline (co)polymer, at least onenucleator and at least one functionalized wax.

The substrates to be bonded include virgin and recycled kraft, high andlow density kraft, chipboard and various types of treated and coatedkraft and chipboard. Composite materials are also used for packagingapplications. These composite materials may include chipboard laminatedto an aluminum foil that is further laminated to film materials such aspolyethylene, Mylar, polypropylene, polyvinylidene chloride, ethylenevinyl acetate and various other types of films. Additionally, these filmmaterials also may be bonded directly to chipboard or Kraft. Theaforementioned substrates by no means represent an exhaustive list, as atremendous variety of substrates, especially composite materials, findutility in the packaging industry.

The hot melt adhesives of the invention find use in, for example,packaging, converting, bag ending and in nonwovens articles. Theadhesives find particular use as case, carton, and tray formingadhesives, and as sealing adhesives, including heat sealingapplications, for example in the packaging of cereals, cracker and beerproducts. Encompassed by the invention are containers, e.g., cartons,cases, boxes, bags, trays, filters, bookbinding and the like, whereinthe adhesive is applied by the manufacturer thereof prior to shipment tothe packager. Following packaging, the container is heat sealed.

Many modifications and variations of this invention can be made withoutdeparting from its spirit and scope, as will be apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only, and the invention is to be limited onlyby the terms of the appended claims, along with the full scope ofequivalents to which such claims are entitled.

EXAMPLE

Heat stress is defined as being the temperature at which a stressed bondfails. In the examples that follow, heat stress, or the ability of a hotmelt to withstand elevated temperature under cleavage forces (alsoreferred to herein as cleavage heat stress), was used to measure heatresistance.

Heat resistance values were measured as described in US 2009/0203847.

1. Four pieces of board 75 mm×25 mm and 75 mm×50 mm were cut fromcorrugated board with the fluting running parallel to the longest edge.On both sides of each board a line was drawn 22 mm from the end asindicated in FIG. 1.

2. Approximately 100 g of hot melt in a small metal container was heatedat the application temperature, 180-185° C.

3. The adhesive was stirred with a spatula to ensure even heatdistribution; the spatula was then lifted out of the adhesive to producea stream of adhesive in the container. This process was repeated foreach sample.

4. The 50 mm board was passed under the stream of adhesive to give abead width of 3 mm along the 25 mm line as shown in FIG. 1 (the speedwith which the board moved determined the bead width and the typicalspeed was about 2 m/sec).

5. The 25 mm board was taken and bonded same side to same side lining up25 mm mark to that of 50 mm board's 25 mm mark as shown in FIG. 2. The25 mm board was positioned in the center of the 50 mm board leavinguncompressed hot melt adhesive on either side, this uncompressedadhesive once cooled can be used to check that the bead width is ±3 mm.

6. The bond was formed within 3 seconds and a 100 g weight placed on thebond area to ensure even bonding pressure. The bond was left at least 24hours before testing.

7. The 25 mm board end of the bonded sample was hole-punched to allow a100 g weight to be hung from it. The sample was attached by the 50 mmpiece of board in an oven so that it was horizontal to the oven shelfwith the 25 mm board facing down using four bulldog clips and a 100weight was attached to it as shown FIG. 3.

8. The oven was turned on and set at a temperature of 40° C. and leftfor 20 minutes. The oven temperature after the initial 20 minutes wasraised by 3° C. every 15 minutes. The oven temperature noted when thesample fails represents the heat resistance of the sample. The reportedheat resistance value is an average value, based on 4 tests.

Set-time is defined as the amount of time the substrates must becompressed together before they can be released. A bond held shorterthan the set time may open up or be of inadequate strength. A bond heldfor the required set time or longer will deliver full adhesiveproperties. The set-time was measured using the method as described inU.S. Pat. No. 5,201,230. A bead of adhesive was applied to a cardboardsubstrate traveling on a belt moving at 30 m/s. The applicationtemperature of the adhesive was 180° C. After an open time of 1 second,another cardboard substrate was applied to the first substrate with aforce of 1 kg. The two substrates were held together for a predeterminedtime, known as “set-time,” and then separated with maximum force. Theset-time is defined as the amount of time required to hold the twosubstrates together before achieving a 100% fibre tear along the bead ofadhesive when the substrates are separated. The reported set-time valueis an average value, based on 3 tests.

Polymer 1 was formed by degrading a single polymer that containedgreater than 75 wt % propene content until it reached a viscosity of1,868 mPa·s at 200° C.

The polymers blends were formed by thermal mechanical degradation of twoolefinic polymers: (i) an ethylene-propylene rubber (EPR) and (ii) asemi-crystalline olefinic polymer which has less than 20 wt % ethyleneor C4-20 alpha olefin comonomers. All of the polymer blends contained atleast 65 wt % polypropylenes and less than 20 wt % ethylene or C₄₋₂₀alpha olefin comonomers. Each polymer blend was thermal mechanicallydegraded until it reached the following viscosity at 200° C. Theviscosities of the polymers were measured with Brookfield Thermosell RVTviscometer, with spindle 27.

The heat of melting and the recrystallization temperature are reportedbelow for Polymer 1 and Polymer Blend E. The heat of melting andrecrystallization temperature values were measured with a DSC (Q2000from TA Instruments) in accordance with ISO 11357-3, with minoradjustments: the cooling and the second heating nm rates were reducedfrom −10° K/min to −5° K/min and the time the sample was held at thelowest temperature, directly following the cooling run, was increasedfrom 5 minutes to 15 minutes. For sample preparation, 3-10 mg of thepolymer/polymer blend was weighed in an aluminum standard crucible witha lid. The sample was then loaded in the DSC and cooled to −90° C. to beequilibrated at that temperature for 20 minutes, then heated from −90°C. to 200° C. with a heating rate of 10° K/min (first heating run),equilibrated at 200° C. for 5 minutes, followed by cooling down to −90°C. with a cooling rate of 5° K/min (cooling run), equilibrated at −90°C. for 15 minutes and then followed by a heating step to 200° C. with aheating rate of 5° K/min (second heating run). The recrystallizationtemperature was calculated from the cooling run and the heat of meltingwas obtained from the second heating run, both values were determined inaccordance with ISO 11357-3. The viscosities (at 190° C.), heats ofmelting and recrystallization temperatures of the functionalized waxes(Epolene E43 and A-C-596P) were also measured as described above.

FIG. 8 is a DSC curve that shows the measurements and integrations ofthe heat of melting and recrystallization temperature for Epolene E43.

Polymer/Polymer Melt viscosity at Heat of Recrystallization Blend 200°C. (mPa · s) Melting (J/g) Temperature (° C.) Polymer 1 1,868 69 99.2Polymer Blend A 2,400 Polymer Blend B 2,000 Polymer Blend C 1,900Polymer Blend D 3,700 Polymer Blend E 1,700 50 92 Melt viscosity atFunctionalized Wax 190° C. (mPa · s) Epolene E43 400 87 113 (WestlakeChemical) A-C-596P 400 70 102 (Honeywell)

Components to Reference and Sample Adhesives made with Polymer 1 arelisted in Table 1. All of the components were heated at 180° C. untilthey were dissolved into a homogenous mixture.

TABLE 1 Adhesive Formulation with a Single Polymer Reference ReferenceReference Sample 4 1 (wt %) 2 (wt %) 3 (wt %) (wt %) Polymer 1 80 80 8080 Arkon M-100 20 20 20 20 (Arakawa Europe) Epolene E43 — 1 — 1 MilladNX 8000 — — 0.2 0.2 (Milikan Chemical) Irganox 1010 (BASF) 0.3 0.3 0.30.3 Heat resistance (° C.) 87 93 81 99 Set time (seconds) 9-10 9 2.52-2.5

As shown in Table 1, the addition of a functionalized wax in theformulation (Ref 2) increased the heat resistance, but the set timeremained high. The addition of a nucleator (Ref 3) decreased the settime of the formulation, but the heat resistance suffered. Only whenboth the functionalized wax and the nucleator are present in theadhesive did the heat resistance and the set time improve. In fact, theaddition of both components significantly improved the heat resistanceand the set speed, and the result produced an effect greater than thesum of their individual component effects.

Components to each adhesive made with Polymer Blend A are listed inTable 2. All of the components were heated at 180° C. until they weredissolved into a homogenous mixture.

TABLE 2 Adhesive Formulation with a Polymer Blend Reference A ReferenceB Reference C Sample D (wt %) (wt %) (wt %) (wt %) Polymer Blend A 63.7563.67 63.18 63.09 Escorez 5400 26.41 26.38 26.17 26.14 (Exxon MobilChemical) Epolene E43 — — 0.90 0.90 Millad NX 8000 — 0.14 — 0.14 EdelexS 946 Oil 9.11 9.10 9.03 9.01 (Shell Chemical) Irganox 1010 0.73 0.710.72 0.72 Heat resistance (° C.) 51 47 63 73 Set time (seconds) 20 3 193

Similar to the results of Table 1, the addition of both functionalizedwax and the nucleator in the adhesive of Table 2 significantly improvedthe heat resistance and the set speed; and the result produced an effectgreater than the sum of their individual component effects.

Adhesives listed in Table 3 were made in the same manner as the adhesivein Table 2.

TABLE 3 Spherulites Reference E Reference F Reference G Sample H (wt %)(wt %) (wt %) (wt %) Polymer Blend B 69.44 68.76 69.31 68.63 Escorez5400 29.76 29.47 29.70 29.41 Epolene E43 — 0.98 — 0.98 Millad NX 8000 —— 0.20 0.20 Irganox 1010 0.80 0.79 0.79 0.78 Figure 4 5 6 7

FIGS. 4-7 are microscopic photographs of spherulites of adhesives ofTable 3. Each adhesive was (1) placed onto a microscope slide and meltedat 180° C., (2) a cover slip was applied onto the adhesive, (3) theentire slide was cooled to room temperature, and (4) a photograph of theslide, with a polarized light and 1000× magnification, was taken.

While the presence of a nucleator or a functionalized wax, alone,decreased the size of the spherulites (compare FIGS. 5 and 6 to FIG. 4),the addition of both components drastically decreased the size of thespherulites (FIG. 7). It is this synergistic effect of both a nucleatorand a functionalized wax that resulted in the significant improvement inheat resistance and set time of the adhesive.

The range of ratio of the nucleator to the functionalized wax was testedand reported in Table 4. The adhesives in Table 4 were prepared in thesame manner as the adhesives in Tables 2 and 3.

TABLE 4 Nucleator: Functionalized Wax Ratio Reference I Reference JReference K Sample L (wt %) (wt %) (wt %) (wt %) Nucleator: Function-N/A 1:567 99:1 1:5 alized wax (ratio) Polymer Blend C 70.14 66.16 69.4469.31 Escorez 5400 29.06 27.41 28.77 28.71 Epolene E43 — 5.67 0.01 0.99Millad NX 8000 — 0.01 0.99 0.20 Irganox 1010 0.80 0.76 0.79 0.79 SetTime (sec) 15.0-17.5 15.0-17.5 3.0 2.0-2.5 Heat resistance (° C.) 63.364.0 57.3 83.0

As shown in Table 4, the ratio of the nucleator to a functionalized waxaffects the performance of the adhesive. Adhesives with the nucleatorand the functionalized wax ratio within the preferred range, 1:500 to10:1 (nucleator to functionalized wax), results in short set-time andhigh heat resistant performance.

Multiple amides components and its derivatives as nucleators were alsotested. The Samples were prepared in the same manner described in Tables1-4.

TABLE 5 Multiple Amides Components as Nucleators Sample M Sample N (wt%) (wt %) Polymer Polymer Blend D Polymer Blend E 79.59 69.34 TackifierEscorez 5380 Escorez 5400 (Exxon Mobil Chemical) 27.73 18.90Functionalized Wax A-C-596P Epolene E43 0.99 1.98 Nucleator IrgaclearXT386 RiKACLEAR PC1 (Milikan Chemical) (Rika International) 0.02 0.148Anti-oxidant Irganox B225 Irganox 1010 (BASF) 0.79 0.50 Heat resistance(° C.) 75 72.3 Set time (seconds) 6-7 6-7

The use of multiple amides as nucleators with functionalized wax alsoresulted in adhesives with short set-time and high heat resistance.

We claim:
 1. An adhesive comprising: (a) a polymer component whichcontains, in polymerized form, at least 65 wt % of propylene, based onthe total weight of the polymer component; (b) from about 0.01 to about1 wt % of a nucleator; (c) from about 0.5 to up to 5 wt % of afunctionalized polypropylene wax; and (d) from 21 to about 60 wt % of atackifier wherein the total weight percent of the adhesive equals to 100wt % and wherein the adhesive has a heat resistance of at least 5° C.greater than an adhesive without the nucleator and the functionalizedpolypropylene wax.
 2. The adhesive of claim 1 wherein the polymercomponent comprises a copolymer of propylene and at least one comonomer,wherein the comonomer is selected from ethylene and/or C₄₋₂₀alpha-olefins.
 3. The adhesive of claim 1 wherein the polymer componentis a polymer blend which comprises a mixture of at least two(co)polymers and each of the (co)polymer contains in (co)polymerizedform at least 65 wt % of propylene, based on the total weight of eachpolymer.
 4. The adhesive of claim 1 wherein the polymer component is apolymer blend which comprises at least one thermomechanical degradedsemi-crystalline polypropylene (co)polymer and at least onethermomechanical degraded elastomeric rubber.
 5. The adhesive of claim 1wherein the nucleator is selected from the group consisting of allose,altrose, fructose, galactose, glucose, gulose, idose, mannose, sorbose,talose, tagatose, arabinose, ribose, ribulose, xylose, xylulose, lyxose,erythrose, threose, sorbitol, xylitol and derivatives thereof and/ormixtures thereof.
 6. The adhesive of claim 5 wherein the nucleator isselected from the group consisting of 1,3: 2,4 dibenzylidene sorbitol,1,2,3,4-di-para-methylbenzylidene sorbitol, 1,2,3,4-di-meta,para-methylbenzylidene sorbitol, bis(4-propylbenzylidene) propylsorbitol and mixtures thereof.
 7. An adhesive comprising: (i) a polymerblend that comprises at least one thermomechanical degradedsemi-crystalline polypropylene (co)polymer and at least onethermomechanical degraded elastomeric rubber; (ii) from about 0.01 toabout 1 wt % of a nucleator selected from the group consisting oforganic acid salts, phosphoric acids, ethylene-(meth)acrylic acidionomers, multiple amides components, sorbitols and their correspondingderivatives thereof; (iii) from about 0.5 to up to 5 wt % of afunctionalized polypropylene wax which is a wax grafted with at leastone olefinically unsaturated dicarboxylic anhydride of less than 12carbon atoms; and (iv) from 21 to about 60 wt % of a tackifier whereinthe total weight percent of the adhesive equals to 100 wt % and whereinthe adhesive has a heat resistance of at least 5° C. greater than anadhesive without the nucleator and the functionalized polypropylene wax.8. The adhesive of claim 7 wherein the polymer component comprises acopolymer of propylene and at least one comonomer, wherein the comonomeris selected from ethylene and/or C₄₋₂₀ alpha-olefins.
 9. The adhesive ofclaim 7 wherein the polymer component is a polymer blend which comprisesa mixture of at least two (co)polymers and each of the (co)polymercontains in (co)polymerized form at least 65 wt % of propylene, based onthe total weight of each polymer.
 10. An adhesive consisting essentiallyof: (a) from about 30 to 78 wt % based on the total weight of theadhesive, of a polymer component which contains, in polymerized form, atleast 65 wt % of propylene, based on the total weight of the polymercomponent; (b) from about 0.05 to about 1 wt %, based on the totalweight of the adhesive, of at least one nucleator; (c) from about 0.01to up to 5 wt %, based on the total weight of the adhesive, of at leastone functionalized polypropylene wax; (d) from 21 to about 50 wt %,based on the total weight of the adhesive, of a tackifier, and (e) from0 to about 10 wt %, based on the total weight of the adhesive, of aplasticizer, stabilizer, and/or additive; wherein the total weightpercent of the adhesive equals to 100 weight percent and wherein theadhesive has a heat resistance of at least 5° C. greater than anadhesive without the nucleator and the functionalized polypropylene wax.11. The adhesive of claim 10 wherein the polymer component comprises acopolymer of propylene and at least one comonomer, wherein the comonomeris selected from ethylene and/or C₄₋₂₀ alpha-olefins.
 12. The adhesiveof claim 10 wherein the polymer component is a polymer blend whichcomprises a mixture of at least two (co)polymers and each of the(co)polymer contains in (co)polymerized form at least 65 wt % ofpropylene, based on the total weight of each polymer.
 13. The adhesiveof claim 10 wherein the polymer component is a polymer blend whichcomprises at least one thermomechanical degraded semi-crystallinepolypropylene (co)polymer and at least one thermomechanical degradedelastomeric rubber.
 14. The adhesive of claim 10 wherein the nucleatoris selected from the group consisting of allose, altrose, fructose,galactose, glucose, gulose, idose, mannose, sorbose, talose, tagatose,arabinose, ribose, ribulose, xylose, xylulose, lyxose, erythrose,threose, sorbitol, xylitol and derivatives thereof and/or mixturesthereof.
 15. The adhesive of claim 14 wherein the nucleator is selectedfrom the group consisting of 1,3: 2,4 dibenzylidene sorbitol,1,2,3,4-di-para-methylbenzylidene sorbitol, 1,2,3,4-di-meta,para-methylbenzylidene sorbitol, bis(4-propylbenzylidene) propylsorbitol and mixtures thereof.